a. Field of the Invention
This invention relates to a camera assembly for the inspection of passageways. In particular this invention relates to a camera assembly for the inspection of wellbores and designed to operate in high temperature environments.
b. Related Art
In oil and gas wells, the wellbore may be open or may be clad with a well casing. Visual inspection of the wellbore is important to check the integrity of the wellbore, and to investigate any downhole problems that may delay or prevent use of the well. For example, it is important to regularly inspect the casings for corrosion and wear.
Although visual inspection of the wellbore is important, the conditions typically found in a wellbore tend to hinder the ability to use many camera systems. Wellbores can have diameters in the range 10 centimeters to 1 meter and can reach depths of hundreds or thousands of meters. In order to inspect these bores, therefore, it is not only necessary to provide a camera system that can operate at these depths, but also to provide the lighting required to be able to capture still images or video in this confined environment.
Furthermore, any camera system must be able to withstand the pressures and temperatures encountered at depth in a borehole. Pressures at these depths can be very large and can reach around 150 MPa, and in addition, temperatures may exceed 100° C.
Typically, downhole camera systems comprise a camera and light source contained in a protective steel sheath. These camera systems are lowered into the wellbore on an electrical cable or a shaft, with the images from the camera being relayed back to the surface where they are displayed and recorded. However, conventional camera systems are not able to withstand the high temperatures for long periods of time, making a thorough visual inspection difficult.
It is known to mount a camera within a vacuum flask housing to protect the image sensor from the high temperatures, however, these systems provide poor image quality.
It is, therefore, an object of the present invention to provide an improved camera system able to operate at high temperatures that overcomes the above problems.